1. Field of the Invention
The present invention relates generally to a baler and, more particularly, is concerned with an improved adjustable rail assembly for providing accurate guidance of the baler plunger during its reciprocatory movements within the bale case.
2. Description of the Prior Art
A conventional hay baler has a fore-and-aft extending bale case and a plunger reciprocable therein, both of which are generally rectangular in cross section. The bale case extends in the direction of travel of the baler across the field and has an inboard side wall provided with an inlet feed opening for crop material. The baler also has a pickup and feeding mechanism to deliver crop material through the inlet feed opening and into the bale case.
The reciprocating plunger operates to compress the crop material within the bale case to form bales. When the plunger is retracted forwardly, the bale case inlet feed opening is open and operation of the feeding mechanism is timed with the plunger reciprocation to deliver a charge of crop material through the inlet feed opening and into the bale case at that moment. When the plunger moves rearwardly on its working stroke to compress the just delivered charge of material, one side face of the plunger closes the inlet feed opening. However, the operation of the feeding mechanism is coordinated with the rearward stroke of the plunger to insure withdrawal of the feeding mechanism from the opening before it is closed by the plunger. Further, in order to separate the crop material within the feeding area outside the bale case from the material just delivered into the bale case by the feeding mechanism, the plunger is provided with a knife with cooperates with a stationary knife positioned vertically and rearwardly along the bale case inlet opening to sever the material during the rearward stroke of the plunger.
From the brief description just given of the basic operating components of the baler, the central role played by the reciprocating plunger in the formation of crop material bales within the baler's bale case will be readily appreciated. To be able to satisfactorily perform its central role, the plunger must have considerable mass and be reciprocated at relatively high speed, such as seventy or more strokes per minute.
Further, it is necessary to suitably support and accurately guide the plunger through such rapid reciprocatory movements within the bale case and also to provide a close operating clearance between the plunger knife and the stationary bale case knife so that the crop material will be properly sheared with each rearward working stroke of the plunger.
A highly satisfactory roller/track arrangement for adjustably supporting the plunger for reciprocation within the bale case is illustrated and described in U.S. Pat. No. 3,059,569 which issued Oct. 23, 1962 to Edwin B. Nolt and is assigned to the same assignee as the present invention. This arrangement allows the respective knives on the plunger and bale case to be precisely set in a desired operating relationship with respect to one another.
Heretofore, for facilitating accurate guidance of the plunger along its support tracks during its reciprocatory movement within the bale case, a fore-and-aft extending arm assembly has been provided, being attached at its rear end to the right side of the plunger, as illustrated and described in U.S. Pat. No. 3,782,275 which issued Jan. 1, 1974 to Neil W. Webster and is assigned to the same assignee as the present invention. The assembly at its forward end rotatably mounts a pair of orthogonally arranged bearing rollers.
Also, as seen in the aforesaid latter patent, the plunger is reciprocably driven through its interconnection with a rotating crank arm by an elongated connecting rod. The connecting rod has a transversely-extending tubular sleeve at its rear end which is pivotally journalled about a transverse bearing shaft on the plunger. At its forward end, the connecting rod is pivotally connected to the outer, free end of the rotating crank arm. Thus, to reciprocably drive the plunger through its forward and rearward strokes, the circular motion at the forward end of the connecting rod is translated into fore-and-aft reciprocatory linear motion at the rear end of the rod, with the rear end of the rod pivoting vertically about the horizontal axis defined by the plunger transverse bearing shaft.
Consequently, a high level of fore-and-aft directed driving force is imposed on the transverse bearing shaft of the plunger through the sleeve at the rear end of the connecting rod. In order to avoid component failure in this area, it is essential that the arm assembly effectively guide the plunger along a straight line true path in order to maintain the plunger bearing shaft in a generally normal or perpendicular alignment to the connecting rod throughout each reciprocatory stroke of the plunger. If the plunger is not free to travel the length of its stroke in a straight line manner without binding or laterally turning relative to the side walls of the bale case, side pressure or transversely directed forces are imposed on the plunger bearing shaft via the connecting arm sleeve which results in severe wear and potentially early failure thereof. Also, severe wear may occur to the components of the plunger roller/track support arrangement as well as to the connecting rod bearing sleeve.
The tendency toward plunger binding resulting from lateral turning of the plunger from its desired straight line path of travel is due to the fact that the horizontally-disposed one of the bearing rollers on the front end of the arm assembly has heretofore been adjusted to track along a rail fixed on the inboard side of the bale case or on the bale case top adjacent the inboard side whereby the plunger will be guided along a path which is parallel to the bale case side wall. In order to achieve accurate, straight-line guidance of the plunger by the arm assembly and thereby provide the desired perpendicular relationship of the connecting rod to the plunger bearing shaft, the side wall of the bale case and the arm assembly must be more or less perfectly straight or parallel relative to the natural path the plunger wants to take.
However, because of the difficulty encountered in maintaining close tolerances during the construction of certain parts and in avoiding warpage due to localized heating at certain areas of parts during the welding of the parts together, something less than straight parts or ones having the exact desired configurations are produced and frequently the assemblies so fabricated may be slightly warped. In particular, the sides of the bale case may become slightly warped during its fabrication or when other components are welded to it. Also, the arm assembly may warp slightly during its construction and attachment to the plunger.
To summarize, adjustment of the horizontal bearing roller of the arm assembly for travel along a path defined by the side of the bale case or by a rail fixed thereon or adjacent thereto which hasn't been accurately aligned with the natural path of the plunger has frequently resulted in a tendency for the plunger to bind, turn or cock sidewise as it moves through its reciprocatory stroke.